This invention relates to pipette applicator devices and has particular utility in connection with antisera applicators in an immunofixation electrophoresis system wherein a standard multi-channel pipette has intra-channel spacing which is inconsistent with the spacing needed for the applicators.
Immunofixation electrophoresis, referred to as IFE, is well-known as a two-stage procedure for detecting the presence of certain proteins in human serum, urine or cerebral spinal fluid. The procedure involves, as a first step, protein fraction resolution by electrophoresis. As a second step, the soluble antigen in each protein fraction is allowed to react with its antibody. The resultant antigen-antibody complexes will precipitate, at a rate dependent upon the proportion of the reactants, temperature, salt concentration and pH. The antigen-antibody complexes are then visualized by staining.
The IFE process is described in greater detail in Gebott et al., U.S. Pat. No. 4,668,363 issued May 26, 1987, which is hereby incorporated by reference. Apparatus and chemicals for performing IFE have been marketed for some time by Helena Laboratories Corporation of Beaumont, Tex.
Typically, a specimen from a single patient is diluted and then placed in multiple sample or application areas (also referred to as zones or lanes) on a single electrophoretic gel plate. The purpose of utilizing multiple sample areas is to enable detection separately of total serum protein, and various proteins such as the immunoglobin heavy chains IgG, IgM, IgA and light chains Kappa and Lambda, or other proteins whose presence or absence may be of importance in medical diagnosis. As known in the prior art, various antisera (i.e., fluid containing the antibody) such as IgG, IgM, etc., are deposited on the appropriate zones or lanes and permitted to react with the antigen in the sample. The term xe2x80x9cincubationxe2x80x9d refers to the time interval during which the antisera and antibody are in contact such that a reaction may occur.
U.S. Pat. No. 5,137,614, issued on Aug. 11, 1992 to Golias, which is hereby incorporated by reference, is directed to a control system for verifying the effectiveness of the chemicals utilized in the immunofixation electrophoresis procedure. This is accomplished without the need to interrupt patient specimen evaluation when chemicals are replenished, since the chemical utilized on the specimens are also utilized in the control test. The control system verifies that the chemicals have retained their lability.
U.S. Pat. No. 3,844,918, issued on Oct. 29, 1974 to Crawley, which is hereby incorporated by reference, is directed to a template which includes an aperture through which serum is received. The template is placed on a mold having an extended portion which passes through the aperture. Gel is coated on one surface of the template. When the gel molds around the portion extending through the aperture, the mold is removed from the template. The template is left with a small cavity in which the serum is placed.
U.S. Pat. No. 5,403,456, issued on Apr. 4, 1995 to Bellon, which is hereby incorporated by reference, is directed to a mask which includes an orifice through which liquid is deposited on the zone of the gel, and a slit through which excess liquid is withdrawn from the zone of the gel after the incubation step. In practice, the mask is placed in close proximity to, but spaced apart from the surface of the gel, the liquid is deposited through the mask onto the gel, the mask is maintained in its relative position during the incubation step, and, thereafter, excess liquid is withdrawn through the mask. Then, of course, the mask, is removed.
It is preferred, for reasons of economy, to evaluate samples of multiple patients simultaneously. This has been accomplished, in the past, using multiple xe2x80x9csetsxe2x80x9d or groups of zones on a single electrophoresis gel. Thus, if six zones are required for the desired analysis for a single patient, and if the samples from as many as six patients are to be evaluated simultaneously, then 6xc3x976 or 36 zones or lanes are used on the electrophoresis gel. As would be expected, after the electrophoresis step, the appropriate antisera must be applied to the corresponding zone for each patient. For example, if blood samples of six patients are being evaluated simultaneously, then after the electrophoresis step, one antisera (e.g., IgG antisera) was applied sequentially to the corresponding zone for each patient using a pipette of the type which has a removable, disposable tip. Then, the tip on the pipette would be removed, and another antisera (e.g., IgM antisera) would be applied sequentially to the corresponding zone for each patient using a second disposable tip. This procedure would be repeated for each of the antisera. Of course, it was possible to apply the various antisera to the corresponding zones for a single patient, and then repeat the process for the next patient, etc., but this would be cumbersome, time consuming, and create a potential for errors because of the large number of pipette tips which would be used, i.e., 36 tips.
As a first improvement on the processing of samples from multiple patients simultaneously, Helena Laboratories Corporation, assignee of the present invention, developed and marketed a system in which samples from as many as six patients, i.e., 36 zones, can be processed simultaneously using, inter alia, a multiple channel pipette for dispensing the six antisera simultaneously onto the six lanes representing a single patient. Then, the pipette is xe2x80x9creloadedxe2x80x9d and antisera dispensed onto the six lanes representing the second patient, etc.
The desire to increase productivity and thus reduce the cost per xe2x80x9ctestxe2x80x9d has resulted in the modification of the electrophoresis gel to accomodate samples from nine patients, i.e., 54 zones. However, since automatic electrophoresis equipment, such as the equipment marketed by Helena Laboratories Corporation under the trademark REP(copyright) already exists, it is not practical to change the size of the electrophoresis gel plate, notwithstanding that 54 zones instead of 36 zones are present. Thus, it should be appreciated that while the overall size of the gel has not changed, the spacing between zones on the gel has changed.
Applicant has discovered, however, that while the electrophoresis equipment manufactured by Helena Laboratories Corporation can process 54 zones simultaneously, there are no multiple channel pipettes which can be used to simultaneously dispense the six antisera on the six zones or lanes corresponding to a single patient, when a 54 zone (i.e., 9 patients) gel is used. Furthermore, the demand for specially designed multiple channel pipettes for the above purpose and the resulting cost is not justified by the quantity of electrophoresis machines involved, even though a large number of tests per se are performed each year. In other words, there is not a suffient number of hospitals and independent laboratories to support a custom-made multiple channel pipette which is dimensioned for 9 patient gel.
The present invention overcomes the difficulties and shortcomings of the prior art by which providing an adapter which may be used on a standard, multiple channel pipette, and which changes the spacing between the replaceable tips, by spreading (or contracting, if necessary) the spacing between the cones of the pipette onto which each removable tip is placed.